The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recently, it has been proposed to use an image forming apparatus including a heat fixing belt with a resistive heat generation layer in an image forming apparatus such as a copier and a printer for forming a toner image by thermally fixing unfixed toner placed on an image support such as plain paper. When power is fed to the resistive heat generation layer, the fixing belt generates heat to thereby achieve toner heat fixing. An image forming apparatus adopting this fixing method excels in shortening its warm-up time, saving its energy and increasing its speed as compared with a conventional method.
On one hand, one method of increasing the amount of heat generated from the heat fixing belt is to decrease the volume resistance value of the resistive heat generation layer. For example, as a technology for the method, it is proposed to disperse conductive materials such as carbon-based conductive agents and metallic particles in materials of a binder (JP 2007-272223 A). This technology requires that the conductive materials be dispersed uniformly to attain a uniform heating generation temperature. JP 2007-272223 A discloses a technology of using carbon nanomaterials and filamentary metallic particles as the conductive materials. However, it is difficult to increase the mixture amount of carbon nanomaterials in terms of price.
JP 2000-058228 A discloses a thin-film resistance heating element using a carbon nanotube and a carbon micro-coil as conductive materials and a toner heating fixing member using the thin-film resistance heating element. However, the thin-film resistance heating element that is formed of a carbon nanotube and a carbon micro-coil decreases in its mechanical strength. It is thus difficult to decrease the volume resistance value by increasing the mixture amount of carbon nanotube and the like.
On the other hand, when an electrode layer to feed power to the resistive heat generation layer is provided on the surface of the resistive heat generation layer, it is difficult to cause the resistive heat generation layer and the electrode layer to adhere firmly to each other, and its long-period use causes the problem that an electrode is peeling off, and the like. JP 2013-122531 A discloses a method of forming an electrode by an electroless plating process in which metallic nanoparticles supplied onto the surface of a resistive heat generation layer are used as a catalyst. However, even with this method, sufficient adhesion has not been achieved.